<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		BMI:<input type="text" id="input1" />
		<button onclick="check()">结果</button>
		<script>
		function check()
		{
			
			var math = parsetInt(input1.value)
			if(math<20)
			{
				alert("及格了！")
			}
			else if(math>20&&math<25)
			{
				document.write("体重适中")
			}
			else
			{
				alert("不及格！")
			}
		}
		</script>
	</body>
</html>
